The assignee of the present invention currently manufactures an ink jet cartridge for use on wide format inkjet plotters having a large off-carrier ink supply and an ink supply hose through which ink is siphoned from the off-carrier supply to continuously replenish an ink reservoir in the cartridge. The cartridge ink reservoir has an opening extending through a female part of a Luer-Lock fitting. The ink supply hose is connected to one end of an opening in the male part of the fitting and an elongated hollow needle extends from the other end of this opening. When the cartridge is installed on the printhead carrier and the two parts of the fitting are mated, ink is siphoned from the off-carrier ink supply into the cartridge reservoir to replace ink drawn from the cartridge reservoir during printing.
The currently manufactured cartridge has a disadvantage in that it can not be filled and tested prior to shipment from the factory. If the opening into the ink reservoir is left open, ink leaks from the cartridge during shipment and storage. On the other hand, the opening can not be closed by a temporary cap because changes in the ambient temperature or pressure during shipment or storage either causes air bubbles to be drawn into the cartridge through apertures in the nozzle plate, or causes ink to be forced from the apertures. Therefore, the presently manufactured cartridge is shipped empty and untested from the factory. Prior to use a customer must fill, prime and test the cartridges. The process is messy, error prone and costly in that many cartridges fail to print properly.
In our copending application Ser. No. 09/074,215 now U.S. Pat. No. 6,095,643 we solve the aforementioned problems by providing a cartridge having partitions dividing the interior of the cartridge into a free ink reservoir communicating with a foam-filled ink reservoir via a passage in one of the partitions, and an air buffer region, the air buffer region being open to the foam filled ink reservoir. The fitting that connects the cartridge to an off-board ink supply is located in the lid or top cover of the cartridge so that when the cartridge is not connected to the off-board ink supply the air buffer region is open to the atmosphere. One of the partitions has an opening therein, aligned with the opening in the fitting, and closed by an elastic septum so that when the fitting is connected to an off-board ink supply the hollow needle extends into the free ink reservoir.
While this solves the problem of ink leakage during shipment and storage, it still requires handling of the ink supply line because cartridges do have to be replaced due to wear of the apertures through which ink is ejected. For obvious reasons it would be advantageous if the user did not have to handle the ink supply line during cartridge replacement.
Furthermore, the cartridge described in our above-mentioned application, like many cartridges using an off-board ink supply, requires two steps to install it in a printer. The ink supply must be connected to the cartridge and electrical connections must be established to the heaters on the cartridge which heat the ink to control ejection of ink during printing. The electrical connections are established at the time the cartridge is mounted on the printhead carrier by providing a tab circuit with contacts on an outer surface of a side wall of the cartridge, these contacts being brought into engagement with contacts provided on the printhead carrier as the cartridge is mounted on the carrier.